Substrate imaging apparatus

ABSTRACT

In one embodiment, a substrate imaging apparatus includes: a rotary holding unit that holds and rotates a substrate; a mirror member having a reflecting surface that opposes an end face of the substrate and a peripheral portion of a back surface of the substrate held by the rotary holding unit, the reflecting surface being inclined with respect to a rotation axis of the rotary holding unit; and a camera having an imaging device that receives both first light and second light through a lens, the first light coming from a peripheral portion of a front surface of the substrate held by the rotary holding unit, and the second light being a reflected light of second light which comes from the end face of the substrate held by the rotary holding unit and is reflected by the reflecting surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/437,869, filed Feb. 21, 2017, and claims the benefit of JapanesePatent Application No. 2016-031361, filed Feb. 22, 2016, the entiretiesof which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a substrate imaging apparatus.

BACKGROUND OF THE INVENTION

At present, a photolithography technique is widely used to form apattern (patterned projections/recesses) on a substrate in fineprocessing of substrates. For example, a process for forming a resistpattern on a semiconductor wafer includes forming a resist film on asurface of the wafer, exposing the resist film with a predeterminedpattern, and allowing the exposed resist film to be reacted with adeveloper to develop the exposed resist film.

In recent years, a liquid immersion exposure technique has been proposedas a technique for obtaining a very fine resist pattern of about 40 nmto 45 nm in line width. When a resist film is subjected to a liquidimmersion exposure, the resist film is exposed while an exposure liquid(e.g., deionized water or the like), which has a refractive index higherthan that of air, is supplied to a space between a wafer and aprojection lens for exposure.

In the course of processing the wafer surface, small particles (foreignmatters) may adhere to the wafer surface (its central portion orperipheral portion) for various reasons. Most particles can be removedby cleaning the substrate surface with a cleaning liquid, but someparticles may remain on the substrate surface. When a wafer havingparticles adhered thereto is loaded into an exposure device, theexposure device is contaminated. In this case, when a succeeding waferis exposed, a particle shape as well as a desired pattern may betransferred. In addition, when the exposure device is contaminated withparticles, it may take a long time to clean the exposure device, whichseriously lowers productivity. Moreover, if a wafer has some defect inthe vicinity of its periphery (for example, flaw, crack, scratch, etc.)the wafer cannot be properly processed. Thus, Patent Document 1(JP2007-251143A), Patent Document 2 (JP2008-135583A) and Patent Document3 (JP11-339042A) each disclose a wafer inspection method including astep of taking images of a peripheral portion of a wafer by means of aplurality of cameras, a step of processing the images, and a step ofjudging the condition of the peripheral portion of the wafer based onthe processed images.

However, in order to inspect surfaces (e.g., upper surface and end face)near the periphery of a wafer, the checking method of Patent Documents 1to 3 takes images the surfaces individually, with the use of theplurality of cameras. Thus, since a large space for installation ofthese cameras is needed, the wafer inspection apparatus may have alarger size as well as an increased cost of the apparatus.

It is conceivable that the plurality of surfaces near the peripheralportion of the wafer are inspected by moving one camera. However, sincea space for installation of a mechanism for moving the camera is needed,the apparatus may have a larger size after all. In addition, since themoving speed of the camera is not so high, it takes a long time toinspect the wafer.

Further, if a plurality of cameras are used, a mechanism for assemblingthe cameras is needed in addition to these cameras, which complicatesthe structure. Also if one camera is moved, a mechanism for moving thecamera is needed in addition to the camera, which complicates thestructure. Thus, in the inspection method of Patent Documents 1 to 3, amalfunction of the equipment is more likely to occur, and there is apossibility that the inspection could not be efficiently performed.

SUMMARY OF THE INVENTION

The disclosure describes a substrate imaging apparatus achievingreduction in size and decrease in cost, while avoiding equipmentfailure.

A substrate imaging apparatus according to one aspect of the disclosurecomprises: a rotary holding unit that holds and rotates a substrate; amirror member having a reflecting surface that opposes an end face ofthe substrate and a peripheral portion of a back surface of thesubstrate held by the rotary holding unit, the reflecting surface beinginclined with respect to a rotation axis of the rotary holding unit; anda camera having an imaging device that receives both first light andsecond light through a lens, the first light coming from a peripheralportion of a front surface of the substrate held by the rotary holdingunit, and the second light being a reflected light of second light whichcomes from the end face of the substrate held by the rotary holding unitand is reflected by the reflecting surface.

In the substrate imaging apparatus according to the one aspect of thedisclosure, the mirror member has the reflecting surface that opposes anend face of the substrate and a peripheral portion of a back surface ofthe substrate held by the rotary holding unit, the reflecting surfacebeing inclined with respect to a rotation axis of the rotary holdingunit. In addition, in the substrate imaging apparatus according to theone aspect of the disclosure, the imaging device receives both the firstlight and the second light through the lens, the first light coming fromthe peripheral portion of the front surface of the substrate held by therotary holding unit, the second light being a reflected light of secondlight which comes from the end face of the substrate held by the rotaryholding unit and is reflected by the reflecting surface. Thus, both theperipheral portion of the front surface of the substrate and the endface of the substrate are simultaneously imaged by the one camera. Thus,since plural cameras are no longer necessary, the space for installationof these cameras is no longer needed. In addition, since a mechanism formoving the camera is unnecessary, the space for installation of such amechanism is not necessary. Namely, the substrate imaging apparatusaccording to the one aspect of the disclosure can have a significantlysimplified structure. As a result, the substrate imaging apparatus canachieve reduction in size and decrease in cost, while avoiding equipmentfailure.

The reflecting surface may be a curved surface that is recessed awayfrom the end face of the substrate held by the rotary holding unit. Inthis case, the size of a mirrored image of the end face of the substratereflected on the reflecting surface is enlarged. Thus, a more detailedimage of the end face of the substrate can be obtained. As a result, byprocessing the image, the end face of the substrate can be moreprecisely inspected.

The substrate imaging apparatus according to the one aspect of thedisclosure may further comprise a focus adjusting lens disposed in anoptical path of the second light extending from the reflecting surfaceto the lens in order to adjust an image forming position, at which animage of the end face of the substrate is formed, onto the imagingdevice. As compared with the length of the optical path of the firstlight extending to the lens, the length of the optical path of thesecond light extending from the reflecting surface to the lens is longerbecause of the length of the second light reflected by the mirrormember. However, in this case, since the image forming position of theend face of the substrate can be adjusted by the focus adjusting lensonto the imaging device, the images of the peripheral portion of thefront surface of the substrate and the end face of the substrate areboth clear. As a result, by processing the image thus taken according tothe above, the end face of the substrate can be more preciselyinspected.

The substrate imaging apparatus according to the one aspect of thedisclosure may further comprise an illuminating unit including a lightsource and a light diffusing member that diffuses light from the lightsource toward a first direction perpendicular to an optical axis of thelight from the light source in order to generate diffused light, whereinthe illuminating unit irradiates the peripheral portion of the frontsurface of the substrate held by the rotary holding unit with thediffused light, and irradiates the reflecting surface of the mirrormember with the diffused light in order to allow the diffused lightreflected by the mirror member to fall on the end surface of thesubstrate held by the rotary holding unit. In this case, since the lightfrom light source is diffused toward the first direction, the diffusedlight enters the end face of the substrate from various directions.Thus, the entire end face of the substrate can be uniformly illuminated.As a result, the end face of the substrate can be more clearly imaged.

The illuminating unit may further include: a light scattering memberthat scatters the light form the light source to generate scatteredlight; and a cylindrical lens that allows the scattered light from thelight scattering member to pass through the light diffusing member, thecylindrical lens being convex toward the light diffusing member, whereinthe cylindrical lens diffuses light coming into the cylindrical lenstoward a second direction perpendicular to an optical axis of the lightemitted from the light source and perpendicular to the first direction.In this case, since the scattered light is diffused toward the first andsecond directions, the diffused light enters the end face of thesubstrate from various directions. Thus, the end face of the substratecan be uniformly illuminated. As a result, the entire end face of thesubstrate can be more clearly imaged.

The substrate imaging apparatus according to the disclosure can achievereduction in size and decrease in cost, while avoiding equipmentfailure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a substrate processing system.

FIG. 2 is a sectional view taken along the II-II line in FIG. 1.

FIG. 3 is a plan view showing unit processing blocks (BCT block, HMCTblock, COT block and DEV block).

FIG. 4 is a sectional view of an inspection unit seen from above.

FIG. 5 is a sectional view of the inspection unit seen from the lateralside.

FIG. 6 is a perspective view showing the inspection unit.

FIG. 7 is a perspective view of a periphery imaging subunit seen fromthe front side.

FIG. 8 is a perspective view of the periphery imaging subunit seen frombehind.

FIG. 9 is a plan view of the periphery imaging subunit.

FIG. 10 is a side view of a two-face imaging module.

FIG. 11 is an exploded perspective view showing an illuminating module.

FIG. 12 is a sectional view taken along the XII-XII line in FIG. 11.

FIG. 13 is a sectional view taken along the XIII-XIII line in FIG. 11.

FIG. 14A is a picture showing a condition where light from a lightsource passed through a light scattering member.

FIG. 14B is a picture showing a condition where the light from the lightsource passed through the light scattering member and the cylindricallens.

FIG. 14C is a picture showing a condition where the light from the lightsource passed through the light scattering member, the cylindrical lensand the light diffusing member.

FIG. 15A is a diagram for explaining an optical path when there existsno focus adjusting lens.

FIG. 15B is a diagram for explaining an optical path when there exists afocus adjusting lens.

FIG. 16 is a perspective view of a mirror member.

FIG. 17 is a side view of the mirror member.

FIG. 18A is a diagram for explaining a condition where light from theilluminating module is reflected by the mirror member.

FIG. 18B is a diagram for explaining a condition where light from awafer is reflected by the mirror member.

FIG. 19A shows an image that is taken when a front surface of a wafer isin focus without using focus adjusting lens.

FIG. 19B shows an image that is taken when an end face of the wafer isin focus without using focus adjusting lens.

FIG. 19C shows an image that is taken when both of the front surface ofthe wafer and the end face are in focus with the use of the focusadjusting lens.

FIG. 20 is a side view of a back surface imaging subunit.

FIG. 21 is a block diagram showing a main part of the substrateprocessing system.

FIG. 22 is a block diagram showing a hardware structure of a controller.

DETAILED DESCRIPTION OF THE INVENTION

It should be firstly noted that the present invention is not limited tothe below-described illustrative embodiments. In the below-describeddescription, the same element or an element having the same function aredesignated by the same reference symbol, and overlapping description isomitted.

<Substrate Processing System>

As shown in FIG. 1, a substrate processing system 1 (substrateprocessing apparatus) includes a coating and developing apparatus 2(substrate processing apparatus) and a controller 10 (control unit). Thesubstrate processing system 1 is equipped with an exposure apparatus 3.The exposure apparatus 3 has a controller (not shown) capable ofcommunicating with the controller 10 of the substrate processing system1. The exposure apparatus 3 is configured to send and receive a wafer W(substrate) to and from the coating and developing apparatus 2, and toperform an exposure process (pattern exposure) of a photosensitiveresist film formed on a front surface Wa of a wafer W (see FIG. 10). Tobe specific, a part to be exposed of the photosensitive resist film(photosensitive coating film) is selectively irradiated with an energybeam (ray) using a suitable method such as liquid immersion exposure.The energy beam may be, for example, ArF excimer laser, KrF excimerlaser, g-ray, i-ray or EUV (Extreme Ultraviolet) ray.

Before the exposure process by the exposure apparatus 3, the coating anddeveloping apparatus 2 performs a process for forming a photosensitiveresist film or a non-photosensitive resist film (collectively referredto as “resist film” herebelow) on the front surface Wa of the wafer W.After the exposure process by the exposure apparatus 3, the coating anddeveloping apparatus 2 performs a process for developing the exposedphotosensitive resist film.

The wafer W may have a circular plate shape or may have a plate shapeother than the circular shape such as a polygonal shape. The wafer W mayhave a cutout formed by partially cutting out the wafer W. The cutoutmay be, for example, a notch (U-shape or V-shaped groove) or a linearlyextending part (so-called orientation flat). The wafer W may be, forexample, a semiconductor substrate, a glass substrate, a mask substrate,an FPD (Flat Panel Display) substrate, or other various substrates. Adiameter of the wafer W may be, for example, about 200 mm to 450 mm.When an edge of the wafer W is beveled (chamfered), the “front surface”in this specification includes the beveled part when seen from the sideof the front surface Wa of the wafer W. Similarly, a “back surface” inthis specification includes a beveled part when seen from the side of aback surface Wb of the wafer W (see FIG. 10). An “end face” in thisspecification includes a beveled part when seen from the side of an endface We of the wafer W (see FIG. 10).

As shown in FIGS. 1 to 3, the coating and developing apparatus 2includes a carrier block 4, a processing block 5 and an interface block6. The carrier block 4, the processing block 5 and the interface block 6are arrayed horizontally.

As shown in FIGS. 1 and 3, the carrier block 4 includes a carrierstation 12 and a loading and unloading unit 13. The carrier station 12supports thereon a plurality of carriers 11. Each carrier 11 cansealingly contain at least one wafer W. A side surface 11 a of thecarrier 11 is provided with an opening and closing door (not shown)through which a wafer W is taken into and out from the carrier 11. Thecarrier 11 is detachably installed on the carrier station 12 such thatthe side surface 11 a faces the loading and unloading unit 13.

The loading and unloading unit 13 is positioned between the carrierstation 12 and the processing block 5. The loading and unloading unit 13has a plurality of opening and closing door 13 a. When the carrier 11 isplaced on the carrier station 12, the opening and closing door of thecarrier 11 faces the opening and closing door 13 a. By simultaneouslyopening the opening and closing door 13 a and the opening and closingdoor in the side surface 11 a, the inside of the carrier 11 and theinside of the loading and unloading unit 13 communicate with each other.The loading and unloading unit 13 incorporates a delivery arm A1. Thedeliver arm A1 takes a wafer W out from the carrier 11 and delivers itto the processing block 5, as well as receives a wafer W from theprocessing block 5 and returns it into the carrier 11.

As shown in FIGS. 1 and 2, the processing block 5 has unit processingblocks 14 to 17. The unit processing blocks 14 to 17 are arranged suchthat the unit processing block 17, the unit processing block 14, theunit processing block 15 and the unit processing block 16 are aligned inthis order from the floor surface side. As shown in FIG. 3, each of theunit processing blocks 14 to 17 has a liquid processing unit U1, athermal processing unit U2 and an inspection unit U3.

The liquid processing unit U1 is configured to supply various processliquids to a front surface Wa of a wafer W. The thermal processing unitU2 is configured to perform a thermal process by heating a wafer W by,e.g., a heat plate and cooling the heated wafer W by, e.g., a coolingplate. The inspection unit U3 is configured to inspect respectivesurfaces (front surface Wa, back surface Wb and end face Wc) of a waferW (which will be described in detail later).

The unit processing block 14 is a lower film forming block (BCT block)configured to form a lower film on a front surface Wa of a wafer W. Theunit processing block 14 incorporates a transfer arm A2 that transfers awafer W to the respective units U1 to U3 (see FIG. 2). The liquidprocessing unit U1 of the unit processing block 14 forms a coating filmby coating a front surface Wa of a wafer W with a coating liquid forforming the lower film. The thermal processing unit U2 of the unitprocessing block 14 performs various thermal processes for forming thelower film. A concrete example of the thermal processes may be a heatingprocess for hardening the coating film into the lower film. The lowerfilm may be an antireflection (SiARC) film, for example.

The unit processing block 15 is an intermediate film (hard mask) formingblock (HMCT block) configured to form an intermediate film on the lowerfilm. The unit processing block 15 incorporates a transfer arm A3 thattransports a wafer W to the respective units U1 to U3 (see FIG. 2). Theliquid processing unit U1 of the unit processing block 15 forms acoating film by coating the lower film with a coating liquid for formingthe intermediate film. The thermal processing unit U2 of the unitprocessing block 15 performs various thermal processes for forming theintermediate film. A concrete example of the thermal processes may be aheating process for hardening the coating film into the intermediatefilm. The intermediate film may be an SOC (Spin On Carbon) film or anamorphous carbon film, for example.

The unit processing block 16 is a resist film forming block (COT block)configured to form a thermosetting resist film on the intermediate film.The unit processing block 16 incorporates a transfer arm A4 thattransfers a wafer W to the respective units U1 to U3 (FIG. 2). Theliquid processing unit U1 of the unit processing block 16 forms acoating film by coating the intermediate film with a coating liquid(resist agent) for forming a resist film. The thermal processing unit U2of the unit processing block 16 performs various thermal processes forforming the resist film. A concrete example of the thermal processes maybe a heating process (PAB: Pre Applied Bake) for hardening the coatingfilm into the resist film.

The unit processing block 17 is a developing block (DEV block)configured to develop an exposed resist film. The unit processing block17 incorporates a transfer arm A5 that transfers a wafer W to therespective units U1 to U3, and a direct transfer arm A6 that transfers awafer W without passing through these units (see FIG. 2). The liquidprocessing unit U1 of the unit processing block 17 develops the exposedresist film by supplying a developer to the resist film. The liquidprocessing unit U1 of the unit processing block 17 supplies a rinseliquid to the developed resist film so as to rinse away dissolvedcomponents of the resist film together with the developer. Thus, theresist film is partly removed, so that a resist pattern is formed. Thethermal processing unit U2 of the unit processing block 16 performsvarious thermal processes for the developing process. A concrete exampleof the thermal processes may be a heating process before the developingprocess (PEB: Post Exposure Bake), a heating process after thedeveloping process (PB: Post Bake) and the like.

As shown in FIGS. 2 and 3, a shelf unit U10 is disposed in theprocessing block 5 on the side of the carrier block 4. The shelf unitU10 extends from the floor surface to the unit processing block 15, andis divided into a plurality of cells aligned in the vertical direction.An elevation arm A7 is provided near the shelf unit U10. The elevationarm A7 moves a wafer W up and down among the cells of the shelf unitU10.

A shelf unit U11 is disposed in the processing block 5 on the side ofthe interface block 6. The shelf unit extends from the floor surface toan upper part of the unit processing block 17, and is divided into aplurality of cells aligned in the vertical direction.

The interface block 6 incorporates a delivery arm A8, and is connectedto the exposure apparatus 3. The delivery arm A8 is configured to take awafer W from the shelf unit U11 and deliver it to the exposure apparatus3, and is configured to receive a wafer W from the exposure apparatus 3and return it to the shelf unit U11.

The controller 10 controls the substrate processing system 1 partly orentirely. Details of the controller 10 will be described later. Thecontroller 10 can send and receive a signal to and from the controllerof the exposure apparatus 3. Due to the cooperation of the respectivecontrollers, the substrate processing system 1 and the exposureapparatus 3 are controlled.

<Structure of Inspection Unit>

Next, the inspection unit U3 is described in more detail with referenceto FIGS. 4 to 20. As shown in FIGS. 4 to 6, the inspection unit U3includes a housing 100, a rotary holding subunit 200 (rotary holdingunit), a front surface imaging subunit 300, a periphery imaging subunit400 (substrate imaging apparatus) and a back surface imaging subunit500. The respective subunits 200 to 500 are accommodated in the housing100. A loading and unloading port 101 is formed in one end wall of thehousing 100, through which a wafer W is loaded to the inside of thehousing 100 and unloaded to the outside of the housing 100.

The rotary holding subunit 200 includes a holding table 201, actuators202, 203 and a guide rail 204. The holding table 201 is structured as asuction chuck that substantially horizontally holds a wafer W bysuction, for example. The shape of the holding table 201 (suction chuck)is not limited, and may be circular, for example. The size of theholding table 201 may be smaller than a wafer W.

The actuator 202 is, e.g., an electric motor that drives the holdingtable 201 for rotation. Namely, the actuator 202 rotates a wafer W heldon the holding table 201. The actuator 202 may include an encoder fordetecting a rotating position of the holding table 201. In this case,positions of the respective surfaces of a wafer W to be imaged by therespective imaging subunits 300, 400, 500 and the rotating position canbe related to each other. If a wafer W has a cutout, the posture of thewafer W can be specified based on the cutout recognized by therespective imaging subunits 300, 400, 500, and the rotating positiondetected by the encoder.

The actuator 203 is, e.g., a linear actuator that moves the holdingtable 201 along the guide rail 204. Namely, the actuator 203 allows awafer W held on the holding table 201 to be transferred between one endand the other end of the guide rail 204. Thus, the wafer W held on theholding table 201 can be moved between a first position near the loadingand unloading port 101, and a second position near the periphery imagingsubunit 400 and the back surface imaging subunit 500. The guide rail 204extends linearly (e.g., like a straight line) in the housing 100.

The front surface imaging subunit 300 includes a camera 310 (imagingmeans) and an illuminating module 320. The camera 310 and theilluminating module 320 constitute a set of imaging modules. The camera310 includes a lens and one imaging device (e.g., CCD image sensor, CMOSimage sensor, etc.). The camera 310 opposes the illuminating module 320(illuminating unit).

The illuminating module 320 includes a half mirror 321 and a lightsource 322. The half mirror 321 is disposed in the housing 100 such thatit is inclined at substantially 45° with respect to the horizontaldirection. The half mirror 321 is located above an intermediate portionof the guide rail 204 such that the half mirror 321 intersects the guiderail 204 when viewed from above. The half mirror 321 has a rectangularshape. The length of the half mirror 321 is larger than the diameter ofa wafer W.

The light source 322 is located above the half mirror 321. The lightsource 322 is longer than the half mirror 321. Light emitted from thelight source 322 passes through the whole half mirror 321 to traveldownward (toward the guide rail 204). The light having passed throughthe half mirror 321 is reflected by an object located below the halfmirror 321, and is again reflected by the half mirror 321. The lightpasses through the lens of the camera 310 and enters the imaging deviceof the camera 310. Namely, the camera 310 can take an image of an objectpresent in an irradiation area of the light source 322 through the halfmirror 321. For example, when the holding table 201 holding a wafer W ismoved by the actuator 203 along the guide rail 204, the camera 310 cantake an image of the front surface Wa of the wafer W which passesthrough the irradiation area of the light source 322. Data of the imagetaken by the camera 310 is transmitted to the controller 10.

As shown in FIGS. 4 to 10, the periphery imaging subunit 400 includes acamera 410 (imaging means), an illuminating module 420 and a mirrormember 430. The camera 410, the illuminating module 420 (illuminatingunit) and the mirror member 430 constitute a set of imaging modules. Thecamera 410 includes a lens 411 and one imaging device 412 (e.g., CCDimage sensor, CMOS image sensor, etc.). The camera 410 opposes theilluminating module 420.

As shown in FIGS. 7 to 13, the illuminating module 420 is located abovethe wafer W held on the holding table 201. The illuminating module 420includes a light source 421, a light scattering member 422 and a holdingmember 423. As shown in FIGS. 11 to 13, the light source 421 is composedof, for example, a housing 421 a and a plurality of LED point lightsources 421 b disposed in the housing 421 a. These LED point lightsources 421 b are arranged in a line along the radial direction of thewafer W.

As shown in FIGS. 7 to 13, the light scattering member 422 is connectedto the light source 421 so as to overlap with the light source 421. Asshown in FIGS. 11 to 13, the light scattering member 422 has athrough-hole 422 a that extends along the direction in which the lightsource 421 and the light scattering member 422 overlap with each other.An inner wall surface of the through-hole 422 a is mirror finished. Forthe mirror finish, the inner wall surface may be plated with electrolessnickel so as to form a plating film 422 b. Thus, when light from thelight source 421 enters the through-hole 422 a of the light scatteringmember 422, the incident light is irregularly reflected by the platingfilm 422 b, as shown in FIGS. 12 and 13. Therefore, scattered light isgenerated in the light scattering member 422 (see FIG. 14A).

As shown in FIGS. 7 to 13, the holding member 423 is connected to thelight scattering member 422 so as to overlap with the light scatteringmember 422. As shown in FIGS. 10 to 13, the holding member 423 has athrough-hole 423 a and an intersection hole 423 b that intersects thethrough-hole 423 a. The through-hole 423 a extends along a direction inwhich the light scattering member 422 and the holding member 423 areoverlapped with each other. The intersection hole 423 b extends from oneside surface of the holding member 423 toward the through-hole 423 aalong a direction perpendicular to the through-hole 423 a. Theintersection hole 423 b is connected to the through-hole 423 a.

As shown in FIGS. 7 to 13, the holding member 423 holds therein a halfmirror 424, a cylindrical lens 425, a light diffusing member 426, andfocus adjusting lens 427. As shown in FIGS. 10 and 12, the half mirror424 is disposed on an intersection part of the through-hole 423 a andthe intersection hole 423 b such that the half mirror 424 is inclined atsubstantially 45° with respect to the horizontal direction. The halfmirror 424 has a rectangular shape.

As shown in FIGS. 10 to 13, the cylindrical lens 425 is disposed betweenthe holding member 423 and the half mirror 424. As shown in FIGS. 10 to12, the cylindrical lens 425 is a convex cylindrical lens that is convextoward the half mirror 424. An axis of the cylindrical lens 425 extendsin a direction in which the plurality of LED point light sources 421 bare aligned. When scattered light from the light scattering member 422enters the cylindrical lens 425, the scattered light is enlarged along acircumferential direction of the cylindrical surface of the cylindricallens 425 (see FIG. 14B).

As shown in FIGS. 10 to 13, the light diffusing member 426 is disposedbetween the cylindrical lens 425 and the half mirror 424. The lightdiffusing member 426 is a sheet-shaped member having a rectangularshape, and diffuses light having passed through the cylindrical lens425. Thus, diffused light is generated by the light diffusing member 426(see FIG. 14C). For example, the light diffusing member 426 may have anisotropic diffusing function for diffusing incident light toward all thedirections of the surface of the light diffusing member 426, or may havean anisotropic diffusing function for diffusing incident light towardthe axial direction of the cylindrical lens 425 (directionsperpendicular to the circumferential direction of the cylindricalsurface of the cylindrical lens 425).

As shown in FIGS. 7, 8, 11 and 12, the focus adjusting lens 427 isdisposed in the intersection hole 423 b. As long as the focus adjustinglens 427 is a lens having a function for varying a synthetic focallength with respect to the lens 411, the configuration of the focusadjusting lens 427 is not limited. The focus adjusting lens 427 may be alens having a parallelepiped shape, for example.

Suppose that only the lens 411 is used. In this case, as shown in FIG.15A, light from point A nearer to the lens 411 passes through the lens411 and focuses on the imaging device 412, and light from point Bfarther from the lens 411 passes through the lens 411 and focuses on apoint deviated from the imaging device 412 (behind the imaging device412). Thus, the image of the point A taken by the imaging device 412 isclear (in focus), but the image of the point B taken by the imagingdevice 412 is likely to be unclear (out of focus). On the other hand,suppose that there is the focus adjusting lens 427. In this case, asshown in FIG. 15B, light from the point B farther from the lens 411 isrefracted by the focus adjusting lens 427, and then the light passesthrough the lens 411 and focuses on the imaging device 412. Due to theexistence of the focus adjusting lens 427, when the image of the point Bis seen through the focus adjusting lens 427, the point B looks like asif the Point B was located at a C point coplanar with the point A. Thus,when seen from the lens 411, the distance between the point A and thelens 411, and a distance between the seeming position of the Point B (Cpoint position) and the lens 411 are identical to each other.Accordingly, the light from the point A and the light from the Point Bboth focus on the imaging device 412. As a result, the images of thepoint A and the point B taken by the imaging device 412 are both clear.The above explanation similarly applies also to a case in which thefocus adjusting lens 427 is a bifocal lens which has two portions withdifferent refractive powers.

As shown in FIGS. 7, 10, 12, 13 and 16, the mirror member 430 isdisposed below the illuminating module 420. As shown in FIGS. 7, 10, 12,13, 16 and 17, the mirror member 430 includes a body 431 and areflecting surface 432. The body 431 is made of an aluminum block.

As shown in FIGS. 7, 13 and 17, when a wafer W held by the holding table201 is located at the second position, the reflecting surface 432opposes an end face We of the wafer W and a peripheral portion Wd of aback surface Wb of the wafer W. The reflecting surface 432 is inclinedwith respect to the rotary axis of the holding table 201. The reflectingsurface 432 is mirror finished. For example, a mirror sheet may beattached to the reflecting surface 432. Alternatively, an aluminumplating may be provided to the reflecting surface 432, or an aluminummaterial may be vapor-deposited on the reflecting surface 432.

The reflecting surface 432 is a curved surface that is recessed awayfrom the end face Wc of the wafer W held on the holding table 201.Namely, the mirror member 430 is a concave mirror. Thus, a mirror imageof the end face Wc of the wafer W reflected on the reflecting surface432 is enlarged. A radius of curvature of the reflecting surface 432 maybe about 10 mm to 30 mm, for example. A divergence angle θ (see FIG. 17)of the reflecting surface 432 may be about 100° to 150°. The divergenceangle θ of the reflecting surface 432 herein means an angle defined bytwo planes circumscribing the reflecting surface 432.

In the illuminating module 420, light emitted from the light source 421is scattered by the light scattering member 422, enlarged by thecylindrical lens 425, and diffused by the light diffusing member 426.Thereafter, the light passes through the whole half mirror 424 to traveldownward. The diffused light having passed through the half mirror 424is reflected by the reflecting surface 432 of the mirror member 430located below the half mirror 424. When a wafer W held on the holdingtable 201 is located at the second position as shown in FIGS. 13 and18A, the diffused light having been reflected by the reflecting surface432 mainly reaches the end face Wc of the wafer W (if the periphery ofthe wafer W has a beveled part, particularly an upper end of the beveledpart) and the peripheral portion Wd of the front surface Wa.

The light having been reflected from the peripheral portion Wd of thefront surface Wa of the wafer W is not directed toward the reflectingsurface 432 of the mirror member 430 but is reflected again by the halfmirror 424 (see FIG. 18B). The light then passes through the lens 411 ofthe camera 410 to enter the imaging device 412 of the camera 410,without passing through the focus adjusting lens 427. On the other hand,the light having been reflected from the end face Wc of the wafer W isreflected sequentially by the reflecting surface 432 of the mirrormember 430 and the half mirror 424. The light then passes sequentiallythrough the focus adjusting lens 427 and the lens 411 of the camera 410to enter the imaging device 412 of the camera 410. Thus, the opticalpath length of the light coming from the end face Wc of the wafer W tofall on the imaging device 412 of the camera 410 is longer than theoptical path length of the light coming from the peripheral portion Wdof the front surface Wa of the wafer W to fall on the imaging device 412of the camera 410. The optical path difference between these opticalpaths may be about 1 mm to 10 mm, for example. Thus, the imaging device412 of the camera 410 receives both the light which comes from theperipheral portion Wd of the front surface Wa of the wafer W and thelight which comes from the end face Wc of the wafer W. Namely, when thewafer W held by the holding table 201 is located at the second position,the camera 410 can image both the peripheral portion Wd of the frontsurface Wa of the wafer W and the end face Wc of the wafer W. Data ofthe images taken by the camera 410 are transmitted to the controller 10.

If the peripheral portion Wd of the front surface Wa of the wafer W isfocused without the existence of the focus adjusting lens 427, the imageof the peripheral portion Wd of the front surface Wa of the wafer W,which is taken by the camera 410, is clear, but the image of the endface Wc of the wafer W, which is taken by the camera 410, is likely tobe unclear (see FIG. 19A), because of the optical path difference. Onthe other hand, if the end face of the wafer W is focused without theexistence of the focus adjusting lens 427, the image of the end face Wcof the wafer W is clear, but the image of the peripheral portion Wd ofthe front surface Wa of the wafer W imaged by the camera 410 is likelyto be unclear (see FIG. 19B), because of the optical path difference.However, since there actually exists the focus adjusting lens 427 in theoptical path of the light extending from the reflecting surface 432 ofthe mirror member 430 to the lens 411, an image forming position, atwhich an image of the end face Wc of the wafer W is formed, can beadjusted onto the imaging device 412, even though there is the opticalpath difference (see FIG. 15B). Thus, both the images of the peripheralportion Wd of the front surface Wa of the wafer W and the end face Wc ofthe wafer W, which were imaged by the camera 410, are clear (see FIG.19C).

As shown in FIGS. 4 to 9 and 20, the back surface imaging subunit 500includes a camera 510 (imaging means) and an illuminating module 520(illuminating unit). The camera 510 and the illuminating module 520constitute a set of imaging modules. The camera 510 includes a lens 511and one imaging device 512 (e.g., CCD image sensor, CMOS image sensor,etc.). The camera 510 opposes the illuminating module 520 (illuminatingunit).

The illuminating module 520 is located below the illuminating module420, and below the wafer W held by the holding table 201. As shown inFIG. 20, the illuminating module 520 includes a half mirror 521 and alight source 522. The half mirror 521 is inclined at substantially 45°with respect to the horizontal direction. The half mirror 521 has arectangular shape.

The light source 522 is located below the half mirror 521. The lightsource 522 is longer than the half mirror 521. Light emitted from thelight source 522 passes through the whole half mirror 521 to travelupward. The light having passed through the half mirror 521 is reflectedby an object located above the half mirror 521, and is again reflectedby the half mirror 521. Then, the light passes through the lens 511 ofthe camera 510 to enter the imaging device 512 of the camera 510.Namely, the camera 510 can image an object present in an irradiationarea of the light source 522 through the half mirror 521. For example,when the wafer W held by the holding table 201 is located at the secondposition, the camera 510 can image the back surface Wb of the wafer W.Data of the image imaged by the camera 510 are transmitted to thecontroller 10.

<Structure of Controller>

As shown in FIG. 21, the controller 10 includes, as functional modules,a reading unit M1, a storage unit M2, a processing unit M3 and aninstruction unit M4. These functional modules merely correspond to thefunctions of the controller 10 for the sake of conveniences, and do notnecessarily mean that a hardware constituting the controller 10 isdivided into these modules. The respective functional modules are notlimited to modules whose functions are realized by executing a program,but may be modules whose functions are realized by a dedicated electriccircuit (e.g., logic circuit) or an integrated circuit (ASIC:Application Specific Integrated Circuit).

The reading unit M1 reads out a program from a computer-readablerecording medium RM. The recording medium RM records a program foroperating respective units of the substrate processing system 1. Therecording medium RM may be, for example, a semiconductor memory, anoptical memory disc, a magnetic memory disc, or a magneto optic memorydisc.

The storage unit M2 stores various data. The storage medium M2 storesvarious data for processing a wafer W (so-called process recipes), setdata inputted by an operator through an external input apparatus (notshown) and so on, in addition to a program read out by the reading unitM1 from the recording medium RM and data of images imaged by the cameras310, 410, 510.

The processing unit M3 processes various data. For example, theprocessing unit M3 generates, based on various data stored in thestorage unit M2, signals for operating the liquid processing unit U1,the thermal processing unit U2 and the inspection unit U3 (for example,the rotary holding subunit 200, cameras 310, 410, 510, illuminatingmodules 320, 420, 520). In addition, the processing unit M3 processesdata of images imaged by the cameras 310, 410, 510, and judges whether awafer W has a defect or not. If it is judged that the wafer W has adefect, the processing unit M3 generates a signal for stopping theprocess to the wafer W.

The instruction unit M4 transmits signals generated by the processingunit M3 to the respective apparatuses.

A hardware of the controller 10 is formed of one or more controlcomputer(s), for example. The controller 10 has a circuit 10A as ahardware configuration, which is shown in FIG. 22, for example. Thecircuit 10A may be formed of an electric circuitry. Specifically, thecircuit 10A includes a processor 10B, a memory 10C (storage unit), astorage 10D (storage unit), a driver 10E and an input and output port10F. The processor 10B cooperates with at least one of the memory 10Cand the storage 10D to execute a program, so that a signal is inputtedand outputted through the input and output port 10F, whereby theaforementioned respective functional modules are realized. The memory10C and the storage 10D function as the storage unit M2. The driver 10Eis a circuit for driving the respective apparatuses of the substrateprocessing system 1. Signals are inputted and outputted through theinput and output port 10F, between the driver 10E and the variousapparatuses of the substrate processing system 1 (for example, rotatingunit 21, holding unit 22, pumps 32, 42, valves 33, 42, thermalprocessing unit U2, holding table 201, actuators 202, 203, cameras 310,410, 510, light sources 322, 421, 522).

In this embodiment, although the substrate processing system 1 has onecontroller 10, the substrate processing system 1 may have a group ofcontrollers (control unit) formed of the plurality of controllers 10.When the substrate processing system 1 has a group of controllers, theabove-described functional modules may be respectively realized by theone controller 10, or may be realized by a combination of two or morecomputers 10. When the controller 10 is composed of a plurality ofcomputers (circuits 10A), the above-described functional modules may berealized by one computer (circuit 10A), or may be realized by acombination of two or more computers (circuits 10A). The controller 10may have the plurality of processors 10B. In this case, theabove-described functional modules may be respectively realized by oneprocessor 10B, or may be realized by a combination of two or moreprocessors 10B.

<Operation>

In this embodiment, the mirror member 43 has the reflecting surface 432that opposes the end face We and the peripheral portion Wd of the backsurface Wb of the wafer W held by the holding table 201, the reflectingsurface 432 being inclined with respect to the rotation axis of theholding table 201. In addition, in this embodiment, the imaging device412 of the camera 410 receives, through the lens 411, light which comesfrom the peripheral portion Wd of the front surface Wa of the wafer Wheld by the holding table 201, and the reflected light which comes fromthe end face of the wafer W held by the holding table 201 and isreflected by the reflecting surface 432 of the mirror member 430. Thus,both the peripheral portion Wd of the front surface Wa of the wafer Wand the end face Wc of the wafer W are simultaneously imaged by the onecamera 410. Thus, since plural cameras are no longer necessary, a spacefor installation of such cameras is unneeded. In addition, since amechanism for moving the camera 410 is unnecessary, a space forinstallation of such a mechanism is unneeded. Namely, in thisembodiment, the inspection unit U3 can have a significantly simplifiedstructure. As a result, the inspection unit U3 can achieve reduction insize and decrease in cost, while avoiding equipment failure.

In this embodiment, the reflecting surface 432 is a curved surface thatis recessed away from the end face Wc of the wafer W held by the holdingtable 201. Thus, a mirror image of the end face Wc of the wafer Wreflected on the reflecting surface 432 is enlarged. For example, if thereflecting surface 432 is not a curved surface, the width of the endface Wc of the wafer W in the image on the imaging device is about 20pixels. On the other hand, if the reflecting surface 432 is a curvedsurface as described above, the width of the end face Wc of the wafer Win the image on the imaging device is enlarged about 1.5 times in thethickness direction. Thus, a more detailed image of the end face Wc ofthe wafer W can be obtained. As a result, by processing the detailedimage, the end face Wc of the wafer W can be more precisely inspected.

The optical path length of light, which comes from the end face Wc ofthe wafer W and is reflected by the reflecting surface 432 of the mirrormember 430 to reach the lens 411, is longer than the optical path lengthof light, which comes from the peripheral portion Wd of the frontsurface Wa of the wafer W to reach the lens 411, because of thereflection by the mirror member 430. However, in this embodiment, thefocus adjusting lens 427 is disposed in the optical path of the lightextending from the reflecting surface 432 of the mirror member 430 tothe lens 411. The focus adjusting lens 427 is configured to adjust animage forming position, at which the image of the end face Wc of thewafer W is formed, onto the imaging device 412. Thus, owing to the focusadjusting lens 427, the image forming position of the end face Wc of thewafer W can be adjusted onto the imaging device 412, whereby both theimages of the peripheral portion Wd of the front surface Wa of the waferW and the end face Wc of the wafer W are clear. As a result, byprocessing the clear image, the end face Wc of the wafer W can be moreprecisely inspected.

In this embodiment, the illuminating module 420 irradiates thereflecting surface 432 of the mirror member 430 with diffused light inorder to allow the diffused light from the illuminating module 420 whichis reflected by the reflecting surface 432 of the mirror member 430, tofall on the end face Wc of the wafer W held by the holding table 201.Thus, the diffused light enters the end face Wc of the wafer W fromvarious directions. Thus, the entire end face Wc of the wafer W can beuniformly illuminated. As a result, the end face Wc of the wafer W canbe imaged more clearly.

In this embodiment, light emitted from the light source 421 is scatteredby the light scattering member 422, enlarged by the cylindrical lens 425and further diffused by the light diffusing member 426. Thus, thediffused light enters the end face Wc of the wafer W from variousdirections. Thus, the entire end face Wc of the wafer W can be uniformlyilluminated. As a result, the end face Wc of the wafer W can be imagedmore clearly.

Other Embodiments

The embodiment according to the disclosure has been described in detail,but the above embodiment can be variously modified within the scope ofthe present invention. For example, as long as the reflecting surface432 is inclined with respect to the rotation axis of the holding table201 and opposes the end surface Wc and the back surface Wb of the waferW held by the holding table 201, the reflecting surface 432 has anothershape (e.g., flat shape) other than a curved face.

It is not necessary for the periphery imaging subunit 400 to include thefocus adjusting lens 427.

It is not necessary for the periphery imaging subunit 400 to include anyof the light scattering member 422, the cylindrical lens 425 and thelight diffusing member 426.

The inspection unit U3 may be disposed in the shelf units U10, U11. Forexample, the inspection unit U3 may be provided in the cells of theshelf units U10, U11, which are located correspondingly to the unitprocessing units 14 to 17. In this case, a wafer W is directly deliveredto the inspection unit U3 by the arms A1 to A8 that transport the waferW.

The invention claimed is:
 1. A substrate imaging apparatus comprising: arotary holding unit that holds and rotates a substrate; a mirror memberhaving a reflecting surface that opposes an end face of the substrateand a peripheral portion of a back surface of the substrate held by therotary holding unit, the reflecting surface being inclined with respectto a rotation axis of the rotary holding unit; a first camera having animaging device that receives both first light and reflected lightthrough a first lens, the first light coming from a front surface of thesubstrate held by the rotary holding unit, and the reflected light beingsecond light which comes from the end face of the substrate held by therotary holding unit and is then reflected by the reflecting surface; afirst light source disposed above the front surface of the substrateheld by the rotary holding unit; a first half mirror disposed betweenthe first light source and the front surface of the substrate held bythe rotary holding unit, and configured to transmit light coming fromthe first light source therethrough toward the substrate held by therotary holding unit and reflect the first light and the reflected lighttoward the first camera; a component member having a light path holethrough which the first light and the reflected light travel beforereaching the first lens, wherein a focus adjusting lens is disposed inthe light path hole; and the focus adjusting lens configured to adjustan image forming position, at which an image of the end face thesubstrate is formed, onto the imaging device; wherein the focusadjusting lens is interposed in an optical path of the second lighttraveling from the reflecting surface of the mirror member to the firstlens such that the first light does not pass through the focus adjustinglens but the reflected light passes through the focus adjusting lens,wherein the first camera and the first half mirror are arranged in ahorizontal direction.
 2. The substrate imaging apparatus according toclaim 1, wherein the first light is light coming from a peripheralportion of the front surface of the substrate.
 3. The substrate imagingapparatus according to claim 1, wherein the reflecting surface is acurved surface that is recessed away from the end face of the substrateheld by the rotary holding unit.
 4. The substrate imaging apparatusaccording to claim 3, wherein the reflecting surface has a radius ofcurvature within a range from 10 mm to 30 mm.
 5. The substrate imagingapparatus according to claim 1, further comprising a second camerahaving an imaging device that receives a third light coming from a backsurface of the substrate held by the rotary holding unit through asecond lens.
 6. The substrate imaging apparatus according to claim 5,further comprising: a second light source disposed below the backsurface of the substrate held by the rotary holding unit; and a secondhalf mirror disposed between the second light source and the backsurface of the substrate, and configured to transmit light coming fromthe second light source therethrough and reflect the third light;wherein the second camera and the second half mirror are arranged in ahorizontal direction.
 7. The substrate imaging apparatus according toclaim 6, wherein the first camera is configured to image an imagingrange which does not overlap an irradiation range irradiated with lightfrom the second light source, as viewed from the above.
 8. A substrateimaging apparatus comprising: a rotary holding unit that holds androtates a substrate; a mirror member having a reflecting surface thatopposes an end face of the substrate and a peripheral portion of a backsurface of the substrate held by the rotary holding unit, the reflectingsurface being inclined with respect to a rotation axis of the rotaryholding unit; a first camera having an imaging device that receives bothfirst light and reflected light through a first lens, the first lightcoming from a front surface of the substrate held by the rotary holdingunit, and the reflected light being second light which comes from theend face of the substrate held by the rotary holding unit and is thenreflected by the reflecting surface; a first light source disposed abovethe front surface of the substrate held by the rotary holding unit; afirst half mirror disposed between the first light source and the frontsurface of the substrate held by the rotary holding unit, and configuredto transmit light coming from the first light source therethrough towardthe substrate held by the rotary holding unit and reflect the firstlight and the reflected light toward the first camera; a third camerahaving an imaging device that receives fourth light coming from thefront surface of the substrate held by the rotary holding unit through athird lens; a third light source disposed below the front surface of thesubstrate held by the rotary holding unit; and a third half mirrordisposed between the third light source and the front surface of thesubstrate, and configured to transmit a light coming from the thirdlight source therethrough and reflect the fourth light; wherein thefirst camera and the first half mirror are arranged in a horizontaldirection; wherein the third camera and the third half mirror arearranged in a horizontal direction.
 9. The substrate imaging apparatusaccording to claim 8, further comprising a drive unit configured to movethe rotary holding unit in a horizontal direction, wherein the thirdcamera is configured to image the front surface of the substrate held bythe rotary holding unit that is being moved by the drive unit.
 10. Thesubstrate imaging apparatus according to claim 8, further comprising: adrive unit configured to move the rotary holding unit in a horizontaldirection, wherein the third camera is configured to image the frontsurface of the substrate held by the rotary holding unit that is beingmoved by the drive unit, wherein the third half mirror extends in acrossing direction that crosses, as viewed from above, a direction inwhich the substrate held by the rotary holding unit is moved by thedrive unit, and wherein the third half mirror has a length, measured inthe crossing direction, greater than a diameter of the substrate. 11.The substrate imaging apparatus according to claim 9, further comprisinga housing containing the mirror member and the drive unit, wherein thehousing has a loading and unloading port through which the substrate isloaded and unloaded to and from the housing, wherein the mirror memberis disposed in the housing on a side farther from the loading andunloading port, and wherein the drive unit is configured to move therotary holding unit such that the substrate held by the rotary holdingunit moves between a location near the loading and unloading port and alocation near the mirror member.
 12. A substrate imaging apparatuscomprising: a rotary holding unit that holds and rotates a substrate; amirror member having a reflecting surface that opposes an end face ofthe substrate and a peripheral portion of a back surface of thesubstrate held by the rotary holding unit, the reflecting surface beinginclined with respect to a rotation axis of the rotary holding unit; afirst camera having an imaging device that receives both first light andreflected light through a first lens, the first light coming from afront surface of the substrate held by the rotary holding unit, and thereflected light being second light which comes from the end face of thesubstrate held by the rotary holding unit and is then reflected by thereflecting surface; a first light source disposed above the frontsurface of the substrate held by the rotary holding unit; a first halfmirror disposed between the first light source and the front surface ofthe substrate held by the rotary holding unit, and configured totransmit light coming from the first light source therethrough towardthe substrate held by the rotary holding unit and reflect the firstlight and the reflected light toward the first camera; and a focusadjusting lens configured to adjust an image forming position, at whichan image of the end face the substrate is formed, onto the imagingdevice; wherein the focus adjusting lens is interposed in an opticalpath of the second light traveling from the reflecting surface of themirror member to the first lens such that the first light does not passthrough the focus adjusting lens but the reflected light passes throughthe focus adjusting lens, wherein the focus adjusting lens is a bifocallens which has two portions with different refractive powers, whereinthe first camera and the first half mirror are arranged in a horizontaldirection.
 13. The substrate imaging apparatus according to claim 12,wherein the first light is coming from a peripheral portion of the frontsurface of the substrate.
 14. The substrate imaging apparatus accordingto claim 12, wherein the reflecting surface is a curved surface that isrecessed away from the end face of the substrate held by the rotaryholding unit.
 15. The substrate imaging apparatus according to claim 14,wherein the reflecting surface has a radius of curvature within a rangefrom 10 mm to 30 mm.
 16. The substrate imaging apparatus according toclaim 12, further comprising a second camera having an imaging devicethat receives a third light coming from a back surface of the substrateheld by the rotary holding unit through a second lens.
 17. The substrateimaging apparatus according to claim 16, further comprising: a secondlight source disposed below the back surface of the substrate held bythe rotary holding unit; and a second half mirror disposed between thesecond light source and the back surface of the substrate, andconfigured to transmit light coming from the second light sourcetherethrough and reflect the third light; wherein the second camera andthe second half mirror are arranged in a horizontal direction.
 18. Thesubstrate imaging apparatus according to claim 17, wherein the firstcamera is configured to image an imaging range which does not overlap anirradiation range irradiated with light from the second light source, asviewed from above.